Question

Spore formation is not a method of reproduction in bacteria.

Answer 1

Spore, a reproductive cell capable of developing into a new individual without fusion with another reproductive cell. Spores differ from gametes which fuse in pairs to give rise to a new individual.

Complete answer:
Bacterial spores serve as a resting, dormant stage within bacterial life cycle. Spore production is especially common among Bacillus and Clostridium bacteria, several species of which are disease-causing. Many bacterial spores are highly durable and might germinate even after years of dormancy.
Sporulation refers to formation of spores from vegetative cells during unfavorable environmental conditions. It's an adaptive response which allows organism to survive in adverse conditions like radiation, extreme heat or cold, lack of nutrition.

Compared to vegetative cells, spores are multilayered structures which are dormant. These characteristics make it possible for a few of the spores to preserve genetic material of the organism during harsh environmental conditions. During certain unfavorable conditions, a number of the vegetative cells undergo a series of morphological changes that ultimately produce spores.
A majority of spore-forming bacteria are Gram-negative bacilli. These include aerobic Bacillus and anaerobic Clostridium species. Although some Gram-negative bacteria are shown to be capable of manufacturing spores. Depending on the kind of bacteria, four forms of spores are produced.

1)Endospores: Endospores are the foremost common forms of spores. They're typically produced by Clostridium, Bacillus and Sporosarcina bacteria.
2)Cysts: Cysts are a bunch of cells which join together to survive harsh environmental conditions. When conditions within the environment become unfavorable, the cells move in an exceedingly manner that enables them to survive.
3)Myxospores: A myxospore may be a kind of spore that's produced by myxobacteria/ Myxobacterates.
4)Exospores: Exospores are a sort of spore that are produced by members of the phylum Actinobacteria. These spores are produced through the budding of mycelium and may survive in harsh environmental conditions better than the vegetative cells.

Note: Although unfavorable conditions like diminishing sources of nutrition play a very important role in sporulation, therein they trigger the method; sporulation doesn't necessarily start happening instantly. Rather, the bacteria will start by trying to maneuver to a region with favorable conditions.
In the event that food sources diminish, the bacteria, using such structures will try to move to a replacement location through such processes as chemotaxis.